Checking "Background Audio (Experimental)" results in a rejection of my app in the Apple App store with the following explanation:

"Your app declares support for audio in the UIBackgroundModes key in your Info.plist, but we were unable to play any audible content when the app was running in the background.

"Next Steps

"The audio key is intended for use by apps that provide audible content to the user while in the background, such as music player or streaming audio apps. Please revise your app to provide audible content to the user while the app is in the background or remove the "audio" setting from the UIBackgroundModes key."